/* 
 * ConceptualCouponDAO.java
 *
 * Created on March 5, 2007, 4:23 PM
 *
 */

package edu.byu.isys413.jjenkins.data;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.LinkedList;
import java.util.List;

 /**
 * This class contains methods to create, read, update and delete the 
 * coupon Object. It also contains methods to read an object by
 * serveral different criteria. All interaction between the object 
 * and the database is done through this class. 
 * 
 * @author      Jeff Jenkins
 * @version     1.0
 * 
 */
public class ConceptualCouponDAO {
    
    private static ConceptualCouponDAO instance = null;
    
    /**
     * Creates a new instance of ConceptualCouponDAO
     */
    private ConceptualCouponDAO() {
    }
    
        /* This method implements the singleton pattern. It insures that only
     * on instance of ConceputalCouponDAO exists
     *
     * @return: ConceputalCouponDAO instance */
    
    public static synchronized ConceptualCouponDAO getInstance() {
        if (instance == null) {
            instance = new ConceptualCouponDAO();
        }
        return instance;
    }
    
    /* This method creates a new ConceptualCouponBO with a unique QUID, puts the interest
     * in cache, and then returns it to the calling method.
     *
     * @return: ConceptualCouponBO
     * @throws: DataException
     */
    
    public ConceptualCouponBO create() throws DataException {
        try {
            
            String id = GUID.generate();
            ConceptualCouponBO object = new ConceptualCouponBO();
            object.setId(id);
            Cache.getInstance().put(object.getId(), object);
            return object;
        } catch (Exception e) {
            throw new DataException("Could not create GUID", e);
        }
        
    }
    
    
    /**
     * This is the public read statement.  It loads an existing record
     * from the database.
     *
     * @Par: String: id
     * @Return: ConceptualCouponBO
     * @Throws: DataException
     */
    public synchronized ConceptualCouponBO read(String id) throws DataException {
        
        // Checks to see if the item is in cache
        Cache cache = Cache.getInstance();
        ConceptualCouponBO object = (ConceptualCouponBO)cache.get(id);
        try {
            
            // Gets connection
            ConnectionPool connPool = ConnectionPool.getInstance();
            Connection conn = connPool.get();
            
            // If the item is not in cache a connection is checked out and
            // The item is read from the database.
            if(object == null){
                try {
                    //reads in object
                    object = read(id, conn);
                    
                }catch (SQLException e) {
                    conn.rollback();
                    throw new DataException("Could not retrieve record for id=" + id, e);
                }
            }
            
            // connection committs and is returned.
            conn.commit();
            connPool.release(conn);
            
            
            
        } catch (SQLException e) {
            throw new DataException("Could not retrieve record for id=" + id, e);
        } catch (DataException e) {
            throw new DataException("Could not retrieve record for id=" + id, e);
        } catch (ConnectionPoolException e) {
            throw new DataException("Could not retrieve record for id=" + id, e);
        }
        
        // Return object
        return object;
    }
    
    /**
     *  This is a package method that is called by the public read (above) or
     *  by another DAO.  Either way we already have a connection to the database
     *  to use.  The user (controller) code never calls this one directly, since
     *  it can't know about Connection objects or SQLExceptions.
     *
     *  @Par: String: id, Connection conn
     *  @Return: ConceptualCouponBO
     *  @throws: DataException, SQLException
     */
    synchronized ConceptualCouponBO read(String id, Connection conn) throws SQLException, DataException {
        
        
        // Checks to see if the item is in cache
        Cache cache = Cache.getInstance();
        ConceptualCouponBO object = (ConceptualCouponBO)cache.get(id);
        
        // Quieries that database
        if(object == null){
            
            PreparedStatement pstmt = conn.prepareStatement("SELECT * FROM conceptual_coupon WHERE conceptual_coupon_id = ?");
            pstmt.setString(1, id);
            pstmt.execute();
            ResultSet rs = pstmt.getResultSet();
            
            if (rs.next()) {
                object = new ConceptualCouponBO();
                object.setId(rs.getString("conceptual_coupon_id"));
                object.setAmount(rs.getDouble("amount"));
                             
                
                // Sets already in database
                object.setObjectAlreadyInDB(true);
                
                // adds to cache
                cache.put(object.getId(), object);
                
            }else{
                throw new DataException("Object was not found in the database.");
            }
        }
        
        
        // returns object
        return object;
    }
    
    /**
     * This is the public save method.  It is what is called when
     * the user (controller) code wants to save or update an object
     * into the database.
     *
     * @par ConceptualCouponBO object
     * @throws DataExcpetion
     */
    public synchronized void save(ConceptualCouponBO object) throws DataException {
        try {
            
            
            // retrieve a database connection from the pool
            ConnectionPool connPool = ConnectionPool.getInstance();
            
            Connection conn = connPool.get();
            
            
            try {
                
                // Saves Interest
                save(object, conn);
                
            }catch (SQLException e) {
                conn.rollback();
                throw new DataException("Could not save record for" + object.getId(), e);
            }
            
            // connection committs and is returned.
            conn.commit();
            connPool.release(conn);
            
            // touch the cache for the object
            Cache.getInstance().touch(object.getId());
            
            
            
        } catch (DataException e) {
            throw new DataException("Could not save record for" + object.getId(), e);
        } catch (ConnectionPoolException e) {
            throw new DataException("Could not save record for" + object.getId(), e);
        } catch (SQLException e) {
            throw new DataException("Could not save record for" + object.getId(), e);
        }
        
        
    }
    
    /**
     *  This is a package method that is called by the public save (above) or
     *  by another DAO.  Either way we already have a connection to the database
     *  to use.  The user (controller) code never calls this one directly, since
     *  it can't know about Connection objects or SQLExceptions.
     *
     *  By having other DAOs call this save method (rather than update or
     *  insert below, each DAO in a chained save (like the CustomerDAO calling
     *  MembershipDAO calling InterestDAO save chain) can independently decide
     *  whether to udpate or insert the BO it's saving.  That's why I made
     *  update and insert private rather than package level -- if you call
     *  them directly from another DAO, this DAO can't decide whether it's
     *  object needs to be inserted or updated.
     *
     *  @par: ConceptualCouponBO, Connection
     *  @throws: SQLException, DataException
     */
    synchronized void save(ConceptualCouponBO object, Connection conn) throws SQLException, DataException {
        
        // check the dirty flag in the object.  if it is dirty,
        // run update or insert
        if (object.isDirty()) {
            if (object.isObjectAlreadyInDB()) {
                update(object, conn);
            }else{
                insert(object, conn);
            }
            object.setDirty(false);
        }
        
        
        
    }
    
    /**
     * This method is really a part of save(bo, conn) above.  It could be
     * embedded directly in it, but I've separated it into it's own method
     * to isolate the SQL udpate statement and make it more readable.  But
     * logically, it's really just a part of save.
     *
     * @Par ConceptualCouponBO object
     */
    private synchronized void update(ConceptualCouponBO object, Connection conn) throws SQLException, DataException {
        
        PreparedStatement pstmt = conn.prepareStatement("UPDATE conceptual_coupon SET conceptual_coupon_id = ?, amount = ?, WHERE conceptual_coupon_id = ?");
        pstmt.setString(1, object.getId());
        pstmt.setDouble(2, object.getAmount()); 
        pstmt.setString(3, object.getId());
        
        
        pstmt.execute();
        
    }
    
    /**
     * This method is really a part of save(bo, conn) above.  It could be
     * embedded directly in it, but I've separated it into it's own method
     * to isolate the SQL insert statement and make it more readable.  But
     * logically, it's really just a part of save.
     *
     * @Par ConceptualCouponBO object
     */
    private synchronized void insert(ConceptualCouponBO object, Connection conn) throws SQLException, DataException {
        
        // Creates prepared statemetn
        PreparedStatement pstmt = conn.prepareStatement("INSERT INTO conceptual_coupon VALUES(?, ?)");
        pstmt.setString(1, object.getId());
        pstmt.setDouble(2, object.getAmount()); 
        
        //Executes prepated statement
        pstmt.execute();
        
        //Sets already in database true
        object.setObjectAlreadyInDB(true);
        
    }
    
    
    /* We intentionally do not allow a ConceptualCouponBO object to be deleted because
     * it could mess up relationships in the database. Obmitting the delete
     * also prevents fraud. */
    
    public synchronized void delete(CustomerBO customer)throws DataException{
    /* We intentionally do not allow a ConceptualCouponBO object to be deleted because
     * it could mess up relationships in the database. Obmitting the delete
     * also prevents fraud. */
        throw new DataException("You can not delete a ConceptualCouponBO");
    }
    
    public synchronized List<ConceptualCouponBO> readAll() throws SQLException, DataException {
        
        List coupons = new LinkedList();
        
        try {
            
            // Gets connection
            ConnectionPool connPool = ConnectionPool.getInstance();
            Connection conn = connPool.get();
            
        // prepares statemnt
        
        PreparedStatement pstmt = conn.prepareStatement("SELECT conceptual_coupon_id FROM conceptual_coupon");
        pstmt.execute();
        ResultSet rs = pstmt.getResultSet();
        
        
        while(rs.next()){
            String line_id = rs.getString("conceputal_coupon_id");
            coupons.add(read(line_id, conn));
        }
        
            // connection committs and is returned.
            conn.commit();
            connPool.release(conn);
            
            
            
        } catch (SQLException e) {
            throw new DataException("Could not retrieve record", e);
        } catch (DataException e) {
            throw new DataException("Could not retrieve record", e);
        } catch (ConnectionPoolException e) {
            throw new DataException("Could not retrieve record", e);
        }
        

        
        return coupons;
    }
}
